The invention relates generally to devices employed in so-called tractor pulling contests wherein several tractors are successively connected to a device in which a load is shifted along a frame from over a set of ground engaging wheels supporting the rearward end of the frame to over a ground engaging sled which supports the forward end of the frame and is adapted to be pulled by a tractor. Movement of the weight toward the sled gradually increases the resistance offered to the tractor by the device being pulled. The relative pulling power of competing tractors can readily be determined by measurement of the respective distances through which each of the tractors was able to pull the device.
Reference is made to my U.S. Pat. No. 3,741,010 issued June 26, 1973 and incorporated herein by reference. This application discloses subject matter which constitutes an improvement to the subject matter disclosed in U.S. Pat. No. 3,741,010.